Refrigerating apparatus



Dec. 29, 1936. J s K 2,066,235

REFRIGERATING APPARATUS Filed Dec. 30, 1931 ms ATTORNEYS.

Patented-Dee. 29, 1 936? UNITED ST TE PATENT emce- 6 ,2 a I I a I Jacob l ry mesne assignments, to General Motors a corporation of Delaware Application December 30, 1931, Serial no. 583,925 3 Claims- (Cl. 62-4) The present invention relates to refrigerating,

apparatus and the controlthereof.

One of the objects of the present invention is v to prevent the formation of such quantity of 5 ice on a cooling unit of a refrigerating apparatus which would be detrimental to theeflicient operation of the apparatus. 7

It isa further object of the present-invention to provide mechanism which automatically will 10 prevent an excess accumulation of ice on the cooling unit.

In carrying out the above objects, it is a still further object of the invention. to modify temporarily and automaticallythe operation of the refrigerating apparatus when a predetermined amount of ice forms about the cooling unit and then automatically restore the apparatus'for normal operation.

. Further objects and advantages ofthe present 20 invention will be apparent from the following description, reference being had to the accompanying drawing, wherein a preferred form of the present -invention is clearly shown.

In' the drawing:

refrigerating system; and

Fig. 2 is a front view of a refrigerator with the cabinet shown partly in section to illustrate by a pipe 22 and is withdrawn therefrom through 40 a pipe 23. The flow of refrigerant from the pipe 22 tothe header 2! is controlled preferably by a float valve (not shown); A plurality of duct loops 24 are connected in parallelcircuit relation to the header and are arranged to surround a 45 freezing space 23 which may be employed,- if

desired, to receive ice trays or the like.

Any suitable means may be utilized for circulating a refrigerating medium through the cooling unit 24, the particular circulating means 50 herein shown comprises a compressor 30 having i its low pressure side connected to the pipe 23 for withdrawing refrigerant from'the cooling unit and having its high'pressure side connected by a pipe 3| to a condenser 32.- The compressed refrigerant is cooled in any suitable. manner and Fig. 1 is a diagrammatic view of my improved 45, wire 46 and-.wire 41.

the liquid refrigerant is delivered to a receiver 33 t which in turn is connected with the pipe 22 for supplying refrigerant to the cooling'unit 20.

The compressor is driven by a motor 35 through belt and pulley connections 36, 31, and g ls in engagement withcontact 4! 'to complete thecircuit from wire 40 to wire 43. A controller 10 50 arranged to actuate contact with respect to contact 44 normally functions to control operation of the motor 33 and compressor into maintain the cooling unit 23 between certain temperature limits. Any suitable controller may 15 be utilized for this purpose, but I have herein shown for illustrating purposes a metal bellows 5| which is connected by 81 pipe 52 with a thermostat bulb 53. Bulb 53 may contain any'suitable fluid capable of expanding and contractingin 2 response to temperature changes. This bulb 53 is disposed in the food storage compartment of the refrigerator cabinet and isadapted to con-' trol the refrigerating apparatus to maintain the food storage compartment between certain .tem- 5 perature limits.

The fluid contained inbulb 53- upon contracting or expanding,'due to tempera ture changes thereof will collapse or expand the bellows 5| Movement'of bellows 5i actuates a lever 55 which operates a snap switch 56 in- 30 eluding contacts 44 and 45. Therefore when the temperature in the food storage compartment increases to a predetermined high value the bellows it will be caused to expand to actuate snap switch 56 whereby contact-45 is caused to engage 35 contact 44 to thus complete the circuit to the motor 35 and start operation of the refrigerating apparatus. Conversely when the temperature within the food storage compartment is reduced. by the cooling effect produced bythe evaporator. 40

20.- to a-predeterminedlow temperature the bel-- lows 5i will actuate contact 45. to open the electrical circuit to the motor 35. In this manner it is evident that the food storage compartment of the refrigerator cabinet will be maintained 45' 1 between certain temperature limits. 1 I

Through continued use of the refrigerating, apparatus ice collects upon the cooling-"unit dueto condensation of water thereon and thefreezlng of such water, and, if a relatively large amount of 1 4 this ice is formed upon the cooling unit'the 'emrciency of the apparatus is impaired because of the insulating qualities of'th'e ice. Therefore it is desirable to prevent a large formation bf ice upon the'yunit. It is cimtomary to inform the 5 owner of a refrigerating apparatus to provide a manually operated switch for periodically interrupting the circuit to the motor whereby the refrigerating cycles are temporarily interrupted and the cooling unit becomes warm and the ice will melt. It has been found, however, that the owner of such refrigerating system will not give the proper attention. to this defrosting method and permits ice to form on the unit, or, if he does break the circuit, he fails to actuate the switch to again render the refrigerating apparatus operative and the error is not discovered until the products to be refrigerated become relatively warm and often are spoiled. 'In the present invention I have provided means which will automatically provide for the defrosting of the coolone-third oil in the bulb II is satisfactory.

In Fig. 2 the cooling unit It is shown within the cooling compartment ll of a refrigerator cabinet 18. This cabinet is also provided with a storage compartment 11 which is separated from the cooling compartment I! by a partition wall ll. Relatively warm air from the storage compartment 'Il passes into the cooling compartment 1! through a flue "and relatively cold air from the cooling compartment Ii flows through a flue it into the compartment II. The thermo bulb II is, shown in contact with the loops 24 of the cooling unit It and in the path .of the relatively warm air entering through flue I! from the compartment 11. By locating the bulb II as herein shown the cooling unit may normally be operated at a temperature considerably lower than water freezing tem-. perature without freezing a great quantity of the water within the bulb because this bulb is also 7 under the influence of relatively warm: air enteridly, because of the increase in pressure due toing from the compartment II, which air'is above water freezing temperature. Since the water and oil is conflned within the bulb ll, pipe II and bellows it, a temperature'considorably lower than water freezing temperature isnecessary in the bulb ll before the water therein is frozen solfreezing, in such bulb, pipe and bellows.

In view'of the foregoing and as long as the thermostat bulb It, which causes operation of controller ll, tends tomaintain the cooling unit between certain temperature limits, in accordance witlr an increase or decrease in temperature of the food storage compartment 11 of the cabinet ll,

the operating cycles of the refrigerating apparatuswill be normal. However, during such normal operation of the apparatus, for maintaining the cooling unit 20 and consequently the food storage compartment I| between predetermined normal temperature limits, moisture will condense antifreeze upon the'cooling unit. This accumulation of frost or ice on the cooling unit will increase after a certain period of time or continuous use of the apparatus. It has been found that such an accumulation of frost or ice on the cooling unit insulates the unit, from the medium to be cooled thereby, and consequently the cooling unit must be reduced to a lower than normal temperature in order to reduce the medium cooled there- 2,oee,aas

by to the desired low temperature. When this condition occurs it is obvious that the thermostat bulb 53, in the system disclosed, will cause longer than normal operating cycles of the apparatus. Obviously the operating cycles of the apparatus will increase in time indefinitely and may continuously increase unless some provision is provided for defrosting the cooling unit. The longer than normal operating cycles causes the pressure within the cooling unit and likewise the temperature thereof to be reduced to a point below normal. This abnormal decrease in temperature of the cooling unit causes .ail or at least a greater portion of the quantity of water in' the thermostat bulb II to freeze and consequently the expansion of the water during freezing in this bulb creates a pressure and tends to compress the oil in the pipe II' and bellows OI. Compression of the oil thereby causes the bellows it to expand and actuate switch II to separate the movable contact 42 from the stationary contact ll, as shown by the dotted lines in Fig. l of the drawing. thus breaking the electrical circuit to the motor ll of the refrigerating apparatus. The apparatus is thereby rendered inoperative to permit the'relatively warm circulating air in the cabinet to increase the temperature of the ice on the cooling unit or to permit the ice on the cooling unit to be rapidly heated if desired by any suitable auxiliary artiflcial heatingmeans or medium other than the air in the cabinet to cause the ice or frost on the cooling unit II to melt. It is tobe understood that, since the thermostat bulb It is in intimate thermal contact with the metal of the cooling-unit 20, the ice within bulb ll-will not be melted as quickly as the ice on the cooling unit and therefore the cooling unit will be defrosted. that is, substantially all of. the ice accumulated thereon will be removed. As the ice melts from the cooling unit, and the temperature within and of the walls of the cooling unit increases, to a predetermined degree ice within the'thermal bulb II will then also become melted. However, due

to thecontact of bulb II with the cooling unit 2| and also due to the fact that the cutting in or circuit making adjustment of' switch OI is set above -32- l"., at which temperature ice freezes. it is to be understood that substantially shot the ice on the cooling unit will be removed before the ice in bulb ll begins to thaw or melt. Melting of the icein bulb 1| causes the pressure. in bellows t. to again decrease and this bulb then actuates the switch 61 to move contact if into engagement with contact ll to thereby again complete the circuit to the motor 3| through the con-.

troller It. Thus the system is again rendered operative automatically and cyclically operates in response to the controller 50, actuated by thermostat it, and continues such operation until the accumulation of frost or'ice on the cooling unit again increases beyond the desired limit.

It will be apparent from the foregoing that by virtue of the present invention an excess quantity of ice, which is detrimental to the emcient operation of the refrigerating apparatus as herein-- before pointed out, will be prevented from forming upon the cooling unit. It will also be apparent from the foregoing that the control for preventing the formation of ice on the" cooling unit as herein described is entirely automatic and de-.

pends for its operation upon the accumulation" of a predetermined abnormal amount of ice on the cooling unit and upon abnormal operating conditions .of the system such as occurs as stated when a predetermined amount of ice forms on the cooling unit of the system.

While the form of embodiment of the inventionas herein disclosed, constitutes a preferred form,

it is to be understood that other forms might be adopted, all coming within the scope of the claims a a stationary member having a portion thereof in intimate thermal contact with said cooling unit and disposed in the path of warm air circulating into contact with the unit whereby the warm air aii'ects said member to normally maintain the auxiliary means ineffective. and said member being responsive to a predetermined abnormal low temperature of the cooling unit for rendering said auxiliary means effective to prevent starting of the circulating means 'until a higher than normal temperature is reached in the cooling unit.

2; A refrigerating apparatus comprising in combination, a cabinet, an evaporator of a refrigerating system within said cabinet, means forv circulatingliquid refrigerant to and for withdrawing gaseous refrigerant from said evaporator, a control device responsive to the temperature of air in said cabinet for starting and stopping the refrigerant circulating means to maintain said evaporator betweenpredetermined temperiature limits, automatically operated auxiliary means for temporarily rendering said refrigerant circulating means inoperative to permit an increase above normal in the temperature of said evaporator, said auxiliary means including a stationary member having a portion. thereof in intimate thermal contact with said evaporator and disposed in the path of warm air circulating into contact with the evaporator whereby the warm air ail'ects said member to'normally maintain the auxiliary means ineffective, and said member being responsive to a predetermined abnormal low temperature of the evaporator for rendering said auxiliary means effective to prevent starting of the circulating means until a higher than normal temperature is reached in the evaporator.

3. A refrigerating apparatus comprising in combination. a cabinet, an evaporator of a refrigerating system within said cabinet, means for circulating liquid refrigerant to and for withdrawing gaseous refrigerant from said evaporator a'n electrical circuit for said refrigerant circulating means, a control device in said circuit responsive to the temperature of air in said cabinet for starting and stopping the refrigerant circulating means to maintain said evaporator between predetermined temperature limits, a switch interposed in said electrical circuit, a thermostat bulb having a portion thereof in intimate thermal contact with said evaporator and disposed in the path of warm air circulating into contact with said evaporator, said bulb having a connection with said switch for causing operation thereof but being normally maintained ineffective by the warm air circulating into contact with said evaporator, and said bulb being rendered eifective by a predetermined abnormal low temperature of said evaporator to cause operation of said switch and temporary interruption in the operation of the refrigerant circulating means-to permit an increase in temperature of said evaporator above said predetermined temperature limit thereof.

- JACOB SMILACK. 

